Sunday, October 10, 2010

Cities already existed in Ancient times, but the lack of population census makes it difficult to calculate the number of inhabitants of the capital towns of the great empires. However, most historians agree that none of them accounted for one million inhabitants. Roma, at its very peak, was peopled with roughly 750,000 inhabitants; Alexandria had almost half million people; Bagdad, between the years 900 AD and 1500 AD, had a population of about 900,000; and in Constantinople, the capital of the Byzantine Empire, there were as many as half million inhabitants. The first city to reach one million inhabitants is probably Beijing, in 1750.
At the same time, the industrial revolution started in Europe: people would leave the countryside to look for a job in the factories, making cities grow to more than one million inhabitants. For 150 years, all great cities were found in the richest, industrialised countries: London, Paris, Berlin, Vienna, New York, Chicago...
At the beginning of the 20th century there were a dozen cities with more than one million inhabitants, including a novelty: Calcutta, the first great city of the Third World. Soon, metropolis spread all around the world: in 1940 there were 51 cities with one million inhabitants and in 1980 the number amounted to 226. Today, there are so many cities with one million inhabitants that the measuring has changed: in 1990 there were 35 cities with more than five million inhabitants, and ten years later, this number was doubled. And it is growing and growing…
Some great cities have become so large that they have included neighbouring villages and towns, making up continuous urban areas expanding to hundreds of kilometres. Therefore, it is difficult to make a ranking with the largest or most populated cities in the world because it is difficult to check their boundaries. What should be taken into account: the metropolitan area, the urban agglomeration, the city in itself? If we take a look at several rankings of the world’s largest cities, we realise that not even experts agree: in some lists, Seoul is ranked the second largest city because its neighbouring town of Incheon is included as part of its urban agglomeration, whereas some other lists consider that these are two separate towns. Mexico City ranks number three in some lists, but in others it is ranked at the bottom of the top 5, just after New York, Mumbai, Delhi and Sao Paulo.
Nevertheless, all lists agree in two issues: first, the world’s largest city is Tokyo, with 35 millions inhabitants living within its metropolitan area, so it is the most populated town in the world; and secondly, most large towns are found in Third World countries, where population explosion is most obvious. Just to set an example: in the year 1900, Mexico City had only 340,000 inhabitants, which is the current population of Iceland.
Cities are likely to go on expanding, but this growth cannot be unlimited. Our current cities consume three-quarters of the global energy and cause three-quarters of the global pollution. This impact is unsustainable: either reducing the size of cities or reducing consumption and pollution, but there is no other solution.